Diagnostics

Both the Healing and Diagnostics proficiencies aid victims of trauma and disease. But while the Healing proficiency can be used to restore lost hit points, Diagnostics is mainly concerned with determining the cause of the damage and the prognosis; Diagnostics alone will not heal damage.

With a successful proficiency check, a character becomes aware all of the following information applicable to a particular patient:

• If the patient has suffered physical damage, the character can determine the extent of the damage, though he may not be able to ascertain the exact cause (if a victim was attacked by a tiger, the character will know that the victim was clawed by a large animal, but not necessarily the species). The character can recommend treatments and offer prognoses, as with victims of diseases.
• If the patient has been poisoned, the character knows the antidote (if one exists) and how to prepare it. Note that even if the character knows how to prepare an antidote, he may not have access to the necessary ingredients.
• The character knows the name of the disease, its cause, how long the patient has had it, and the optimum treatment. If the patient is treated as specified, he suffers the mildest form of the disease and its shortest duration. If the patient declines treatment, or the treatment doesn't work, the character can determine the patient's prognosis with reasonable accuracy. ("The patient will recover by the end of the month." "The patient will become permanently blind if not treated within a year.") The character may diagnose both natural and magical diseases.
• When examining a corpse, the character can determine how the victim died and approximately how long it's been dead. If the victim died of unnatural causes, the character will only be able to determine the general circumstances of the death. For example, if an evil wizard incinerated the victim with a fireball, a successful diagnostics check might reveal that the victim burned to death very rapidly as a result of some type of magic, but not that it was affected by a fireball.

A character with this proficiency may diagnose himself or any other character, or animals, except for supernatural creatures (such as a ghost or skeleton) and creatures from another plane of existence (like a xorn or aerial servant). He may attempt to diagnose an individual or creature only once.

If a character also has the Healing proficiency, he may modify all Diagnostic checks by +1.

[Complete Paladin's Handbook]